Nowadays, people pay more and more attention to their privacy protection. In many occasions when authentication of a resident identity is required, people do not want to expose their identity information to other people in verification of legitimacy of their identities, so as to fully protect their privacy. For example, when voting on sensitive events, voters want to vote with legal identities without exposure of their identities. In some occasions of consumption, consumers want to pay without exposing their personal information to a merchant. In a case that network users log in a network with controllable identities, they do not want their identity information to be revealed to the public. Currently, demands on these kinds of privacy production keep growing.
There are several techniques for an identity authentication service. At present, an identity authentication method based on public key cryptography is commonly used. By this method, verification of legitimacy of an identity of one to be authenticated is accomplished with digital signature, and at the same time, identity information of the one to be authenticated is exposed to an authenticator. Apparently, there are obvious limitations in this kind of technology during provision of authentication service in the above occasions of application, because privacy of a user can not be protected. In addition, an identity authentication technology with privacy production is required to provide capability of traceability for convenience of control by a controller when necessary.